Cluster ion beam bombardment and Q-ToF-SIMS analysis of large biomolecules

Cluster ion beam effect on large biomolecules is interesting due to differences in ion beam characters from normal ion beams and applications in analysis of the molecules as the cluster ion beam should be more effective in fragmenting large and complicated biomolecules to make study of the complex molecular structure possible. Argon gas cluster ion beam (Ar-GCIB) at 10 keV bombarded samples of DSPC (1,2-distearoyl-sn-glycero-3-phosphocholine, C44H88NO8P, monoisotopic molecular weight 789.6 Da), angiotensin II (C50H71N13O12, monoisotopic molecular weight 1045.5 Da) and leucine enkephalin (C28H37N5O7, monoisotopic molecular weight 555.6 Da). The bombardment-generated fragments were in-situ analyzed and measured using the tandem quadrupole - time-of-flight secondary ion mass spectrometry (Q-ToF-SIMS) technique. The experiment was operated within an integrated system of Ar-GCIB and Q-ToF-SIMS. Two modes, i.e. MS (quadruple off) and MS/MS (quadrupole on), were applied in the ToF-SIMS measurement. Particularly, the secondary ion fragmentation with the collision energy dependence was focused in the study.